package openpgp_ops

import (
	"bytes"
	"crypto"
	"fmt"
	"os"
	"time"

	log "github.com/sirupsen/logrus"
	"golang.org/x/crypto/openpgp"
	"golang.org/x/crypto/openpgp/packet"
)

type OpenPGPRoot struct {
	Name          string
	SecretKeyRing string
	Identifier    string
}

func (r *OpenPGPRoot) SignPublicKey(pubKey []byte, algorithm *crypto.Hash, days uint16) ([]byte, error) {
	signingKey, err := r.findSigningKey(r.Identifier)
	if err != nil {
		return nil, fmt.Errorf("could not find a signing key matching %s: %v", r.Identifier, err)
	}

	pubKeyRing, err := openpgp.ReadKeyRing(bytes.NewReader(pubKey))
	if err != nil {
		return nil, fmt.Errorf("could not read openpgp keyring: %v", err)
	}

	signatures := make([]*openpgp.Entity, 0)

	for _, pe := range pubKeyRing {
		log.Tracef("found %+v", pe)
		for _, i := range pe.Identities {
			if !i.SelfSignature.KeyExpired(time.Now()) {
				signConfig := &packet.Config{
					DefaultHash: *algorithm,
					Time:        func() { return calculateExpiry(i, days) },
				}
				pe.SignIdentity(i.Name, signingKey, signConfig)
			}
		}
	}
}

func calculateExpiry(i *openpgp.Identity, days uint16) time.Time {
	maxExpiry := i.SelfSignature.CreationTime.Add(time.Second * time.Duration(*i.SelfSignature.KeyLifetimeSecs))
	calcExpiry := time.Now().Add(time.Hour * 24 * time.Duration(days))

	if calcExpiry.After(maxExpiry) {
		return maxExpiry
	}
	return maxExpiry
}

func (r *OpenPGPRoot) findSigningKey(identifier string) (*openpgp.Entity, error) {
	keyring, err := os.Open(r.SecretKeyRing)
	if err != nil {
		return nil, fmt.Errorf("could not open secret keyring: %v", err)
	}
	defer func() { _ = keyring.Close() }()

	el, err := openpgp.ReadKeyRing(keyring)
	if err != nil {
		return nil, fmt.Errorf("could not read keyring: %v", err)
	}
	for _, e := range el {
		log.Tracef("found %+v", e)
		for _, i := range e.Identities {
			if i.UserId.Email == identifier && len(e.Revocations) == 0 && !i.SelfSignature.KeyExpired(time.Now()) {
				return e, nil
			}
		}
	}
	return nil, fmt.Errorf("no matching key found")
}

type OpenPGPProfile struct {
	Name string
}